When some mobile wireless communications devices or other wireless communications devices are used near some hearing aid devices, for example, a cochlear implant or a behind-the-ear (BTE) hearing aid having a tone hook and earmold, users often detect a buzzing, humming or whining noise, or other unwanted audible noise such as a Global System for Mobile communications (GSM) buzz, which can be annoying to users. Some hearing aids are more immune than others and have appropriate filters for suppressing this interference noise, while some phones vary in the amount of interference they generate.
The wireless telephone industry has developed ratings for some mobile phones to assist hearing aid users in finding a phone that is more compatible with their hearing aid. Not all phones have been rated, however, but typically, a phone should have a rating listed on its box or on a label on the box. These ratings are not guarantees and some results vary depending on the type of hearing aid and user hearing loss. Some ratings use an M-ratings scale with phones rated M3 or M4 meeting FCC requirements that are likely to generate less interference to hearing aids than phones that are not labeled. M4 is a higher rating. A T-ratings scale occurs with phones rated T3 or T4 meeting FCC requirements, and likely to be useable with a hearing aid telecoil (“T-switch” or “telephone switch”) than unrated phones. T4 is the better quality. Some hearing aid devices, however, do not include telecoils. Also, some hearing aids can be measured for immunity to this type of interference.